Ceramic ultrafiltration devices have been used in the past for filtering fine particles from a variety of fluids, including both gases and liquids, by the action of the pores in the walls of a hollow filament formed from the ceramic. In addition, the ceramic devices can be used in a reverse osmosis system, either as a separate pre-treatment device or as an integral part of the reverse osmosis apparatus, providing support for a reverse osmosis membrane formed on the surface of the ceramic ultrafiltration device.
Particularly advantageous techniques have recently been developed for the preparation of a three dimensional network of rigid, porous hollow filaments of inorganic material. The network is made by coating a continuous combustible core with a paste of the inorganic material, forming the resultant coated core into a network, followed by firing the coated core to burn off the core and consolidate the coating to a rigid porous hollow filament.
While previous ceramic structures have provided excellent performance, continuing effort has been directed to further improve the strength and flux characteristics of such ultrafiltration devices, and to provide greater control over the pore fraction and pore diameter in the hollow filaments.